1. Field of the Invention
The present invention relates to a treatment solution supply method and a treatment solution supply unit for a substrate.
2. Description of the Related Art
In a photolithography process in semiconductor device fabrication processes, for example, resist coating treatment for applying a resist solution to the surface of a wafer to form a resist film, exposure treatment for exposing the wafer in a pattern, developing treatment for performing development treatment for the exposed wafer, and so on are performed in respective processing units to form a predetermined circuit pattern on the wafer by a series of these treatments.
To describe a conventional resist solution supply system of a resist coating unit for performing resist coating treatment referring to FIG. 12, from a gallon bottle 131, for example, which works as a resist solution supply source, through a pipeline 134, which connects the gallon bottle 131 with a resist solution discharge nozzle 133, to the resist solution discharge nozzle 133, a resist solution in the gallon bottle is forcibly fed by a pump 132, so that the resist solution is supplied on a wafer W to the discharge nozzle 133 to perform resist coating treatment. When there are plural gallon bottles, they are sometimes disposed in two tiers up and down due to space restriction.
However, when the level height in the gallon bottle 131 becomes lower as the supply to the resist solution discharge nozzle 133 proceeds, the pressure given on a primary side of the pump 132 changes, which changes a force feed pressure on a secondary side of the pump 132 delicately, and thus, there is a fear that the supply pressure to the resist solution discharge nozzle 133 changes. Then, as a result, since the discharge pressure from the resist solution discharge nozzle 133 changes, and a discharge amount of the resist solution on the wafer W and an impact on the surface of the wafer W fluctuates, there is a fear that a uniform predetermined resist film is not formed.
When the gallon bottles are disposed in two tiers up and down, the level height of the resist solution of the gallon bottle in an upper tier differs greatly from that of the gallon bottle in a lower tier. Therefore, when the resist solution is forcibly fed to the resist solution discharge nozzle 133 selectively from either of the gallon bottles by the above-mentioned pump 132, since from the first the pressure of the primary side of the pump 132 differs in case the resist solution in the upper gallon bottle is selected from in case the lower gallon bottle is selected, the force feed pressure of the secondary side also differs. Consequently, the discharge pressure from the resist discharge nozzle 133 also differs as described above, and the same resist film is not formed on the wafer W when the resist solution is supplied from the upper gallon bottle as when the resist solution is supplied from the lower gallon bottle.
In recent years, especially, since there is a tendency to save a resist solution and so on and make a discharging port small to reduce a discharge amount therefrom, it is feared that even a delicate fluctuation of the discharge pressure may give a great influence on the resist film formed on the wafer.
The present invention is made in consideration of the above-described points, and its object is to maintain the discharge pressure of a treatment solution discharged on a substrate such as a wafer and so on within a predetermined range to perform a substrate processing in a preferable way when the treatment solution is supplied by a pump from a solution supply source to a discharge nozzle such as a nozzle.
Considering the above object, the present invention, from a first viewpoint of the present invention, is a treatment solution supply method for supplying, with a treatment solution in a treatment solution supply source forcibly fed by a pump, the treatment solution on a substrate through a supply path connecting the treatment solution supply source and a discharge nozzle, wherein a storage portion for storing the treatment solution temporarily is disposed in the supply path between the treatment solution supply source and the pump, and another pump for supplying the treatment solution to the storage portion is disposed in the supply path between the storage portion and the treatment solution supply source, and comprising the step of maintaining the level height of the treatment solution in the storage portion at a predetermined height by supplying the treatment solution to the storage portion by the said another pump.
From another viewpoint of the present invention, the present invention is a treatment solution supply method for supplying, with a treatment solution in a treatment solution supply source forcibly fed by a pump, the treatment solution on a substrate through a supply path connecting the treatment solution supply source and a discharge nozzle, wherein a storage portion for storing the treatment solution temporarily is disposed in the supply path between the treatment solution supply source and the pump, and another pump for supplying the treatment solution to the storage portion is disposed in said supply path between said storage portion and said treatment solution supply source, and comprising the step of maintaining the level height of the treatment solution in the storage portion at a predetermined height by operating the pump in association with the said another pump.
From still another viewpoint of the present invention, the present invention is a treatment solution supply method for supplying, with a treatment solution in a treatment solution supply source forcibly fed by a pump, the treatment solution on a substrate through a supply path connecting the treatment solution supply source and a discharge nozzle, wherein a storage portion for storing the treatment solution temporarily is disposed in the supply path between the treatment solution supply source and the pump, and another pump for supplying the treatment solution to the storage portion is disposed in the supply path between the storage portion and the treatment solution supply source, and comprising the step of detecting the level height in the storage portion, and the step of maintaining the level height of the treatment solution in the storage portion at a predetermined height by supplying the treatment solution to the storage portion from the said another pump only when the level height becomes lower than a predetermined value.
From yet another viewpoint of the present invention, the present invention is a treatment solution supply method for supplying, with a treatment solution in a treatment solution supply source forcibly fed by a pump, a predetermined amount of the treatment solution each time on a substrate through a supply path connecting the treatment solution supply source and a discharge nozzle, wherein a storage portion for storing the treatment solution temporarily is disposed in the supply path between the treatment solution supply source and the pump, and another pump for supplying the treatment solution to the storage portion is disposed in the supply path between the storage portion and the treatment solution supply source, and comprising the step of measuring the number of times the predetermined amount is supplied, and the step of maintaining the level height of the treatment solution in the storage portion at a predetermined height by supplying the treatment solution to the storage portion by the said another pump only when the number of supply times exceeds a predetermined number of times.
A treatment solution supply unit of the present invention is a treatment solution supply unit for supplying, with a treatment solution in a treatment solution supply source forcibly fed by a pump, the treatment solution on a substrate through a supply path connecting the treatment solution supply source and a discharge nozzle, comprising a storage portion, disposed in the supply path between said treatment solution supply source and said pump, for storing the treatment solution temporarily, and another pump, disposed in the supply path between the storage portion and the treatment solution supply source, for supplying the treatment solution to the storage portion.
A treatment solution supply unit from another viewpoint of the present invention is a treatment solution supply unit for supplying, with a treatment solution in a treatment solution supply source forcibly fed by a pump, a predetermined amount of the treatment solution on a substrate each time through a supply path connecting the treatment solution supply source and a discharge nozzle, comprising a storage portion, disposed in the supply path between the treatment solution supply source and the pump, for storing the treatment solution temporarily, another pump, disposed in the supply path between the storage portion and the treatment solution supply source, for supplying the treatment solution to the storage portion, a counter for measuring the number of times said predetermined amount is supplied, and a pump controller for controlling the said another pump based on the result measure by the counter.
According to the present invention, the pressure on a primary side of the pump is constantly maintained at the same pressure by disposing the storage portion between the discharge nozzle and the treatment solution supply source, and further by maintaining the level height in the storage portion by the said another pump. Consequently, the force feed pressure on a secondary side of the pump is also kept steady, which keeps the discharge pressure of the treatment solution from the discharge nozzle steady. As a result, the treatment solution with a predetermined discharge pressure is discharged on the substrate, and a substrate processing is performed in a preferable way.
When the level height of the treatment solution in the storage portion is maintained at a predetermined height by operating the pump in association with the said another pump, the same amount of the treatment solution as that supplied on the substrate by the pump can be supplied to the storage portion by the said another pump. Thus, since the level height in the storage portion is maintained at a predetermined height, the discharge pressure of the treatment solution discharged on the substrate from the discharge nozzle is kept steady to perform a substrate processing in a preferable way.
The level height in the storage portion may be maintained at the predetermined height by measuring the number of supplying times by the pump and supplying the treatment solution to the storage pump by the said another pump only when the number of supplying times exceeds a predetermined times, for example, the number of supplying times corresponding to the level fluctuation in the storage portion causing a fluctuation of the discharge pressure to the degree in which a substrate processing is performed without any problem.